Abdominal obesity is essential for the risk of venous thromboembolism in the metabolic syndrome: the Tromso study

Background: The metabolic syndrome is a cluster of cardiovascular risk factors, including abdominal obesity, hypertension, dyslipidemia and insulin resistance, associated with increased risk of cardiovascular diseases and all cause mortality. Objectives: The purpose of the study was to assess the impact of the metabolic syndrome, and its individual components, on the risk of venous thromboembolism (VTE) in a prospective population-based study. Methods: Individual components of the metabolic syndrome were registered in 6170 subjects aged 25-84 years in the Tromso Study in 1994-1995, and first ever VTE events were registered until 1 September 2007. Results: The metabolic syndrome was present in 21.9% (1350 subjects) of the population. There were 194 validated first VTE events (2.92 per 1000 person-years) during a mean of 10.8 years of follow-up. Presence of metabolic syndrome was associated with increased risk of VTE (HR, 1.65; 95% CI, 1.22-2.23) in age- and gender-adjusted analysis. The risk of VTE increased with the number of components in the metabolic syndrome (P < 0.001). Abdominal obesity was the only component significantly associated with VTE in multivariable analysis including age, gender, and the individual components of the syndrome (HR, 2.03; 95% CI, 1.49-2.75). When abdominal obesity was omitted as a diagnostic criterion, none of the other components, alone or in cluster, was associated with increased risk of VTE. Conclusions: Our study provides evidence for the metabolic syndrome as a risk factor for TE. Abdominal obesity appeared to be the pivotal risk factor among the individual components of the syndrome.